The invention relates to generally ophthalmological devices and, more particularly, to contact lenses worn by a patient immediately after an ophthalmologic procedure, such as refractive surgery or dilation of the pupil, to facilitate vision and recovery from the procedure.
There are approximately 150,000,000 eye examinations conducted in the United States per year. During a substantial number of these eye examinations, the doctor dilates the pupil of the patient""s eyes with a pharmaceutical to facilitate examination of the interior of the eye. For example, the doctor will dilate the pupil with an anticholinergic cycloplegic mydriatic to block the responses of the sphincter muscle of the iris and the muscle of the ciliary body to cholinergic stimulation producing pupillary dilation (mydriasis) and paralysis of accommodation (cycloplegia). The peak action of many of the pharmaceuticals can exceed the time required for the examination and, consequently, the pupil remains dilated for some time after the examination is completed. Because the pupil is dilated and the eye cannot accommodate changes in ambient light, it can be difficult for some patients to function under these conditions and patients will refuse dilation and examination because of the inconvenience resulting from the difficulty in seeing clearly with dilated pupils.
Further, many eye examinations result in a patient electing to have refractive surgery to correct impaired vision. The pioneering procedures included radial keratotomy, wherein the cornea was manually cut in a spoked type pattern to flatten the cornea in an effort to correct vision. This procedure had certain drawbacks, such as blurring and difficulty seeing at night. Laser keratectomy later replaced most radial keratotomy as the procedure of choice. In laser keratectomy, a surgical laser was used to flatten the cornea by shaving layers of the cornea away. The current procedure of choice is laser-assisted in-situ keratomilcusis, or LASIK. During LASIK the surgeon uses a microtome or other device to create a corneal flap. The shape of the underlying cornea is modified with an eximer laser or some other laser device or other means, and the flap is replaced.
Regardless of the type of refractive surgery employed, there can be failures. That is, the surgery is unsuccessful in correcting the patient""s vision. In fact, the cornea can remain permanently distorted and the vision impaired. Often the distortion cannot be corrected or the patient refuses to submit to another surgery. If conventional contact lenses are employed in this condition, the posterior curvature has a tendency to conform to the flattened corneal surface and become wrinkled or distorted.
In any event, it would be advantageous to employ a simple, cost-effective device to ameliorate the undesirable effects of an ophthalmological procedure, being either a simple pupillary dilation or an unsuccessful refractive surgery.
The present invention contemplates the use of novel contact lenses which are introduced to the patient""s eye after an ophthalmological procedure, to ameliorate any undesired effect of the procedure. In one embodiment, the invention comprises a lens that reduces the untoward effects of dilation of the pupil. In another embodiment of the invention the lens is designed to normalize the refraction of a cornea distorted through unsuccessful refractive surgery.
One aspect of the invention includes a post-dilation contact lens that reduces the amount of light that enters the eye. The lens comprises a soft contact lens generally having no optical power. The lens has a clear zone of approximately 2 mm to 4 mm in diameter that is positioned over the dilated pupil to allow entry of a limited amount of light for sight. A light-blocking zone comprised of a dark ring surrounds the clear zone. The dark zone can be impenetrable to light or very dark so as to substantially reduce the amount of light that can enter the pupil. The dark zone can be limited in width or can extend to the perimeter edge of the lens.
In another aspect of the invention, the post-procedure lens is a soft contact lens that normalizes the refraction of a distorted cornea. The lens has substantially normally curved front or anterior surfaces that normalizes the light entering the eye. The inside surface, or cornea-contacting surface, is divided into zones. There is a first or central flattened zone of approximately 4 mm to 9 mm, which is positioned over the pupil. The flattened zone is at least one (1) diopter flatter than the adjoining or second zone. That second zone, which surrounds the first zone, generally has a standard radius of curvature that is the same as the flattened zone or steeper. A third zone or radius adjoining the second zone has a curvature which is flatter or longer radius of curvature than the second zone. The lens aligns properly with the shape of the post-refractive surgery cornea to correct refractive light to focus on the retina. The flattened zone conforms to the shape of the cornea at the pupil and conforms to a surgically flattened cornea without collapsing or wrinkling, for example.
Therefore, it is among the various objects of the present invention to provide contact lenses that can be placed on the eye of a subject who has undergone an ophthalmological procedure to amcliorate any undesirable effects of the procedure.
It also is among the various objects of the present invention to provide contact lenses that can be placed on the eye of a subject who has suffered trauma to the eye or has a defect of the eye to ameliorate any undesirable effects of the procedure or the defect.
In one aspect of the invention, the lens is designed to restrict entry of light through a dilated pupil.
In another aspect of the invention, the lens aligns with the shape of a cornea following unsuccessful surgery to correct refractive light to focus on the retina.
These and other aspects and objects of the invention will be apparent to those skilled in the art upon review of the detailed description of the invention.